(12) United States Patent
`Mercado
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 9.223,118 B2
`Dec. 29, 2015
`
`USOO9223118B2
`
`(54) SMALL FORM FACTOR TELEPHOTO
`CAMERA
`
`(71) Applicant: Apple Inc., Cupertino, CA (US)
`
`(72) Inventor: Romeo I. Mercado, Freemont, CA (US)
`
`(73) Assignee: Apple Inc., Cupertino, CA (US)
`(*) Notice:
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21) Appl. No.: 14/069,027
`(22) Filed:
`Oct. 31, 2013
`(65)
`Prior Publication Data
`
`Apr. 30, 2015
`
`(2006.01)
`(2006.015
`(2006.01)
`(2006.01)
`
`3/2009 Shinohara
`7,502,181 B2
`6, 2009 Scherling
`7,554,597 B2
`7,626,767 B2 12/2009 Kudo
`7,663,814 B2
`2/2010 Kitahara
`8,000,031 B1* 8/2011 Tsai .............................. 359,714
`2006, O193063 A1
`8, 2006 Xu et al.
`... 348,208.12
`2009/0015681 A1* 1/2009 Pipkorn ...
`2009.0128927 A1* 5/2009 Chen et al. .................... 359,715
`2010/0315724 A1 12/2010 Fukuta et al.
`2011/01 15965 A1
`5/2011 Engelhardt et al.
`2011/0249347 A1 10, 2011 Kubot
`2012,0081798 A1
`4, 2012
`p al
`2012/0087020 A1* 4/2012 Tang et al. .................... 359,714
`2012fO249815 A1 * 10/2012 Bohn et al. ............... 348,208.99
`2013,0021677 A1
`1/2013 Kubota
`(Continued)
`OTHER PUBLICATIONS
`U.S. Appl. No. 14/291,544, filed May 30, 2014, Romeo I. Mercado.
`(Continued)
`
`Primary Examiner — Nicholas Giles
`Assistant Examiner — Abdelaaziz, Tissire
`(74) Attorney, Agent, or Firm – Robert C. Kowert:
`Meyertons, Hood, Kivlin, Kowert & Goetzel, P.C.
`
`US 2015/O116569 A1
`(51) Int. Cl
`ions/225
`H04N 5/232
`GO2B I3/00
`GO2B 13/02
`ABSTRACT
`(57)
`(52) U.S. Cl.
`A compact telephoto lens system that may be used in a small
`CPC .......... G02B 13/0045 (2013.01); G02B 13/004
`form factor cameras. The lens system may include five lens
`(2013.01); G02B 13/02 (2013.01); H04N 5/225
`(2013.01); H04N5/2254 (2013.01); H04N elements with refractive power. Alternatively, the lens system
`5/232 (2013.O1): H4N 5/2322 (2013.O1
`mav include four lens elements with refractive power. At least
`(
`);
`(
`)
`y
`p
`(58) Field of Classification Search
`one of the object side and image side Surfaces of at least one
`CPC combination set(s) only.
`of the lens elements is aspheric. Total track length (TTL) of
`See application file for complete search history.
`the lens system may be 6.0 mm or less. Focal length f of the
`lens system may be at or about 7.0 mm (for example, within
`a range of 6.5-7.5 mm). Lens elements are selected and con
`figured so that the telephoto ratio (TTL/f) satisfies the relation
`0.74<TTL/f-1.0. Materials, radii of curvature, shapes, sizes,
`spacing, and aspheric coefficients of the lens elements may be
`selected to achieve quality optical performance and high
`image resolution in a small form factor telephoto camera.
`20 Claims, 17 Drawing Sheets
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`9, 2002 Sato
`6,445,513 B2
`5, 2006 Chen et al.
`7,042,656 B2
`7,295.386 B2 11/2007 Taniyama
`7,345,830 B2
`3/2008 Shinohara
`7,453,654 B2 11/2008 Shinohara
`
`total track length (TTL)
`
`Carea
`100
`
`---------s
`
`-----------------------------X
`light from
`object field
`
`photosensor
`20
`
`exampis
`image points
`
`
`
`stop
`
`lens element
`
`lens element
`102
`
`lens element
`i04
`
`
`
`lenseement
`105
`
`Riter l Image
`optional
`plane
`
`Fens system
`110
`
`APPL-1036 / Page 1 of 39
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`

`

`US 9.223,118 B2
`Page 2
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`International Search Report Written Opinion From PCT/US2014/
`061037, Jan. 14, 2015. Apple Inc., pp. 1-10.
`Search Report from the Intellectual Property Office for ROC (Tai
`wan) Patent Application No. 103137485F, Jun. 25, 2015. Apple Inc.,
`pp. 1-5
`2013/0279021 A1 10, 2013 Chen et al.
`1/2015 Dror et al. ..................... ''' Abstract for TW 200632367, published Sep. 16, 2006, Fujinon Cor
`2015.0029601 A1
`OTHER PUBLICATIONS
`poration JP, pp. 1-2.
`
`ck
`
`.
`
`.
`
`.
`
`.
`
`U.S. Appl. No. 14/291,571, filed May 30, 2014, Romeo I. Mercado.
`U.S. Appl. No. 141069,027, filed Oct. 31, 2013, Romeo I. Mercado.
`
`* cited by examiner
`
`APPL-1036 / Page 2 of 39
`APPLE INC v. COREPHOTONICS LTD.
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`

`

`U.S. Patent
`
`Dec. 29, 2015
`
`Sheet 1 of 17
`
`US 9.223,118 B2
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`
`
`
`
`
`
`
`
`
`
`00||
`
`<-----------------------------------------------
`
`APPL-1036 / Page 3 of 39
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`

`

`U.S. Patent
`
`Dec. 29, 2015
`
`Sheet 2 of 17
`
`US 9.223,118 B2
`
`
`
`TANGENTIAL
`
`0.05
`
`SAGTTAL
`
`0.05
`
`100 RELATIVE
`FIELD HEIGHT
`(18.00)0
`
`sa
`
`RELATIVE
`0.84
`FIELD HEIGHT
`(15.30)0
`
`RELATIVE
`0.70
`FIELD HEIGHT
`(12.73)o
`
`RELATIVE
`0.49
`FIELD HEIGHT
`(9,000)
`
`RELATIVE
`0.00
`FIELD HEIGHT
`(0.000)
`
`lens System 110
`RAY ABERRATIONS (
`MILLIMETERS )
`
`650.0000 NM
`
`29 NY
`555.0000 NM
`78. N
`
`APPL-1036 / Page 4 of 39
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`U.S. Patent
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`Dec. 29, 2015
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`Sheet 3 of 17
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`US 9.223,118 B2
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`
`
`
`
`
`
`?-----------------------------------------------
`
`APPL-1036 / Page 5 of 39
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`U.S. Patent
`
`Dec. 29, 2015
`
`Sheet 4 of 17
`
`US 9.223,118 B2
`
`
`
`TANGENTIAL
`
`O.05
`
`100 RELATIVE
`FIELD HEIGHT
`(18.00)0
`
`SAGITTAL
`
`O 05
`
`0.84
`FIELD HEIGHT
`(15.30)0
`
`RELATIVE
`0.70
`FIELD HEIGHT
`(12.73)
`
`RELATIVE
`0.49
`FIELD HEIGHT
`(9,000)
`
`RELATIVE
`O.OO
`FIELD HEIGHT
`(0.000)
`
`lens system 210
`RAY ABERRATIONS (
`MILLIMETERS )
`
`650.OOOONM
`61O.OOOONM
`555.0000 NM
`51O.OOOONM
`47O.OOOONM
`
`APPL-1036 / Page 6 of 39
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`U.S. Patent
`
`Dec. 29, 2015
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`Sheet 5 Of 17
`
`US 9.223,118 B2
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`
`
`
`
`009
`
`?-----------------------------------------------
`
`APPL-1036 / Page 7 of 39
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`

`U.S. Patent
`
`Dec. 29, 2015
`
`Sheet 6 of 17
`
`US 9.223,118 B2
`
`
`
`TANGENTIAL
`
`0.05
`
`100 RELATIVE
`FIELD HEIGHT
`(18.00)0
`
`SAGTTAL
`
`0.05
`
`RELATIVE
`O.84
`FIELD HEIGHT
`(15.30)o
`
`RELATIVE
`O.7O
`FIELD HEIGHT
`(12.73)0
`
`O49 RELATIVE
`FIELD HEIGHT
`(9,000)
`
`RELATIVE
`O.OO
`FIELD HEIGHT
`(0.000)
`
`lens System 310
`RAY ABERRATIONS (
`MILLIMETERS )
`
`650.0000 NM
`610,000ONM
`- 555,000ONM
`SS N
`
`FIG. 6
`
`APPL-1036 / Page 8 of 39
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`

`U.S. Patent
`
`Dec. 29, 2015
`
`Sheet 7 Of 17
`
`US 9.223,118 B2
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`
`
`0077
`
`<-----------------------------------------------
`
`APPL-1036 / Page 9 of 39
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`

`U.S. Patent
`
`Dec. 29, 2015
`
`Sheet 8 of 17
`
`US 9.223,118 B2
`
`
`
`TANGENTIAL
`
`O.05
`
`100 RELATIVE
`FIELD HEIGHT
`(18.00)o
`
`SAGITTAL
`
`O
`
`O84 RELATIVE
`FIELD HEIGHT
`(1530)0
`
`RELATIVE
`O.7O
`FIELD HEIGHT
`(12.73)o
`
`RELATIVE
`0.49
`FIELD HEIGHT
`(9,000)
`
`OOO RELATIVE
`FIELD HEIGHT
`(0.000)
`
`lens system 410A
`RAY ABERRATIONS (
`MILLIMETERS )
`
`650.OOOONM
`610.OOOONM
`555.OOOONM
`51O.OOOONM
`470.OOOONM
`
`FIG. 8
`
`APPL-1036 / Page 10 of 39
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`

`

`U.S. Patent
`
`Dec. 29, 2015
`
`Sheet 9 Of 17
`
`US 9.223,118 B2
`
`
`
`TANGENTIAL
`
`0.05
`
`100 RELATIVE
`FIELD HEIGHT
`(1800)0
`
`SAGITTAL
`
`0.05
`
`Ms
`
`RELATIVE
`0.84
`FIELD HEIGHT
`(1530)o
`
`RELATIVE
`0.7O
`FIELD HEIGHT
`(12.73)o
`
`RELATIVE
`0.49
`FIELD HEIGHT
`(9,000)
`
`RELATIVE
`O.OO
`FIELD HEIGHT
`(0.000)
`
`lens system 410B
`RAY ABERRATIONS (
`MILLIMETERS
`
`650.0000 NM
`610.0000 NM
`- 555.0000 NM
`51O.OOOONM
`470.0000 NM
`
`FIG. 9
`
`APPL-1036 / Page 11 of 39
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`

`

`U.S. Patent
`
`Dec. 29, 2015
`
`Sheet 10 of 17
`
`US 9.223,118 B2
`
`
`
`TANGENTIAL
`
`0.05
`
`100 RELATIVE
`FIELD HEIGHT
`(18.00)o
`
`SAGITTAL
`
`0.05
`
`RELATIVE
`0.84
`FIELD HEIGHT
`(1530)o
`
`RELATIVE
`0.70
`FIELD HEIGHT
`(1273)0
`
`RELATIVE
`0.49
`FIELD HEIGHT
`(9,000)
`
`RELATIVE
`0.00
`FIELD HEIGHT
`(0.000)
`
`lens system 410C
`RAY ABERRATIONS (
`MILLIMETERS )
`
`650.OOOONM
`
`61OOOOONM D 555. OOOONM
`38 N
`
`FIG. 10
`
`APPL-1036 / Page 12 of 39
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`

`

`U
`
`29a2cm
`
`t0%_n8.912320%_e_nMn_P_“8m.Z|YS_:E582fig52_@228
`
`\
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`793:88
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`
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`
`m/M
`
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`\\EmEmE$2EmEmEv.22\
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`m8«8Emvsgmwas
`
`APPL-1036 / Page 13 of39
`APPLE INC V. COREPHOTONICS LTD.
`
`APPL-1036 / Page 13 of 39
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`
`

`

`U.S. Patent
`
`Dec. 29, 2015
`
`Sheet 12 of 17
`
`US 9.223,118 B2
`
`TANGENTIAL
`
`100 RELATIVE
`FIELD HEIGHT
`(1800)o
`
`SAGITTAL
`
`O.025
`
`:- - - -
`-0.025
`\
`-O,025
`
`0.025
`
`RELATIVE
`O.84
`FIELD HEIGHT
`(1530)o
`
`O.025
`
`-
`
`-
`
`is se -- - - -
`
`--
`
`-
`
`sea- -as-
`
`-- us - - -
`
`--- Šs
`
`-0.025
`
`0.025
`
`RELATIVE
`O.69
`FIELD HEIGHT
`(12.60)
`
`-O,025
`
`O.025
`
`-e-a- - - == - - -es
`
`O49 RELATIVE
`FIELD HEIGHT
`(9,000)
`
`OOO RELATIVE
`FIELD HEIGHT
`(0.000)
`
`-O,025
`
`O.025
`
`-0.025
`
`O.025
`
`-- - - -
`
`- ----
`
`- - - - - ---------- a
`
`------------
`
`-0.025
`
`650.0000 NM
`61O.OOOONM
`555, OOOONM
`51O.OOOONM
`470.0000 NM
`
`-0.025
`
`0.025
`
`-0.025
`
`0.025
`
`-0.025
`
`- - - -
`
`---
`
`lens system 510
`RAY ABERRATIONS (
`MILLIMETERS )
`
`FIG. 12
`
`APPL-1036 / Page 14 of 39
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`U.S. Patent
`
`Dec. 29, 2015
`
`Sheet 13 of 17
`
`US 9.223,118 B2
`
`
`
`
`
`sixe
`
`<-----------------------------------------------
`
`APPL-1036 / Page 15 of 39
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`U.S. Patent
`
`Dec. 29, 2015
`
`Sheet 14 of 17
`
`US 9.223,118 B2
`
`TANGENTIAL
`
`O.025
`
`100 RELATIVE
`FIELD HEIGHT
`(18.00).O
`
`SAGITTAL
`
`0.025
`
`u-L - -
`
`- -
`
`-st
`
`RELATIVE
`0.84
`FIELD HEIGHT
`(15.30).O
`
`RELATIVE
`0.69
`FIELD HEIGHT
`(12.60)0
`
`RELATIVE
`0.49
`FIELD HEIGHT
`(9,000).O
`
`RELATIVE
`O.OO
`FIELD HEIGHT
`(0.000).O
`
`-0.025
`
`O.025
`
`-0.025
`
`O.025
`
`
`
`-0.025
`
`O.025
`
`-O.025
`
`O.025
`
`-O.025
`
`-0.025
`
`0.025
`
`-0.025
`
`0.025
`
`-0.025
`
`0.025
`
`-0.025
`
`0.025
`
`-0.025
`
`lens system 610
`RAY ABERRATIONS (
`MILLIMETERS ) || - - - - - - - -
`
`-
`
`-
`
`- -
`
`-
`
`-
`
`650.0000 NM
`610.OOOONM
`555. OOOONM
`51O.OOOONM
`
`470. OOOONM
`
`FIG. 14
`
`APPL-1036 / Page 16 of 39
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`

`U.S. Patent
`
`Dec. 29, 2015
`
`Sheet 15 Of 17
`
`US 9.223,118 B2
`
`
`
`receive light from an Object field through a stop at a first lens
`element Of the Camera
`1100
`
`the light is refracted by the first lens element to a Second
`lenS element
`1102
`
`the light is refracted by the second lens element to a third
`lenS element
`1104
`
`the light is refracted by the third lens element to a fourth lens
`element
`1106
`
`the light is refracted by the fourth lens element to a fifth lens
`element
`1108
`
`the light is refracted by the fifth lens element to forman
`image at an image plane proximate to the Surface Of a
`phOtoSenSOr
`1110
`
`the image is captured by the photosensor
`1112
`
`FIG. 15
`
`APPL-1036 / Page 17 of 39
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`U.S. Patent
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`Dec. 29, 2015
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`Sheet 16 of 17
`
`US 9.223,118 B2
`
`
`
`receive light from an Object field through a stop at a first lens
`element Of the Camera
`1200
`
`the light is refracted by the first lens element to a second
`lenS element
`1202
`
`the light is refracted by the Second lens element to a third
`lenS element
`1204
`
`the light is refracted by the third lens element to a fourth lens
`element
`1206
`
`the light is refracted by the fourth lens element to forman
`image at an image plane proximate to the Surface of a
`photoSenSOr
`1208
`
`the image is captured by the photoSensOr
`1210
`
`FIG. 16
`
`APPL-1036 / Page 18 of 39
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`U.S. Patent
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`Sheet 17 Of 17
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`US 9.223,118 B2
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`
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`
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`APPL-1036 / Page 19 of 39
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`

`1.
`SMALL FORM FACTOR TELEPHOTO
`CAMERA
`
`US 9,223,118 B2
`
`BACKGROUND
`
`1. Technical Field
`This disclosure relates generally to camera systems, and
`more specifically to high-resolution, Small form factor tele
`photo camera systems.
`2. Description of the Related Art
`The advent of small, mobile multipurpose devices such as
`Smartphones and tablet or pad devices has resulted in a need
`for high-resolution, Small form factor cameras for integration
`in the devices. However, due to limitations of conventional
`camera technology, conventional Small cameras used in Such
`devices tend to capture images at lower resolutions and/or
`with lower image quality than can be achieved with larger,
`higher quality cameras. Achieving higher resolution with
`Small package size cameras generally requires use of a pho
`tosensor with Small pixel size and a good, compact imaging
`lens system. Advances in technology have achieved reduction
`of the pixel size in photosensors. However, as photosensors
`become more compact and powerful, demand for compact
`imaging lens system with improved imaging quality perfor
`mance has increased.
`
`10
`
`15
`
`25
`
`SUMMARY OF EMBODIMENTS
`
`35
`
`40
`
`45
`
`Embodiments of the present disclosure may provide a
`30
`high-resolution telephoto camera in a small package size. A
`camera is described that includes a photosensor and a com
`pact telephoto lens system. Embodiments of a compact tele
`photo lens system are described that may provide a larger
`image and with longer effective focal length than has been
`realized in conventional Small form factor cameras. Embodi
`ments of the telephoto camera may be implemented in a small
`package size while still capturing sharp, high-resolution
`images, making embodiments of the camera Suitable for use
`in Small and/or mobile multipurpose devices such as cell
`phones, Smartphones, pad or tablet computing devices, lap
`top, netbook, notebook, Subnotebook, and ultrabook comput
`ers. In some embodiments, a telephoto camera as described
`herein may be included in a device along with a conventional,
`wider-field small format camera, which would for example
`allow the user to select between the different camera formats
`(telephoto or wide-field) when capturing images with the
`device.
`Embodiments of a compact telephoto lens system are
`described that include five lens elements with refractive
`power. In addition, embodiments of a compact telephoto lens
`system are described that include four lens elements with
`refractive power. In embodiments, at least one of the object
`side and image side Surfaces of at least one of the lens ele
`ments is aspheric.
`In at least Some embodiments, the telephoto lens system
`may be a fixed telephoto lens system configured such that the
`effective focal length f of the lens system is at or about 7.0
`millimeters (mm) (e.g., within a range of 6.0-8.0 mm), the
`F-number (focal ratio) is within a range from about 2.4 to
`about 10.0, the field of view (FOV) is at or about 36 degrees,
`and the total track length (TTL) of the lens system is within a
`range of about 5.2 to about 7.0 mm. More generally, the lens
`system may be configured such that that the telephoto ratio
`(TTL/f) satisfies the relation:
`
`50
`
`55
`
`60
`
`65
`
`2
`In the example embodiments described herein, the tele
`photo lens system may be configured such that the effective
`focal length fof the lens system is 7.0 mm, and the F-number
`is 2.8. However, note that the focal length (and/or other
`parameters) may be scaled or adjusted to meet specifications
`of optical, imaging, and/or packaging constraints for other
`camera system applications. In addition, in some embodi
`ments, the telephoto lens system may be adjustable. For
`example, the telephoto lens system may be equipped with an
`adjustable iris or aperture stop. Using an adjustable aperture
`stop, the F-number (focal ratio, or f7ff) may be dynamically
`varied within some range, for example within the range of 2.8
`to 10. In some embodiments, the lens system may be used at
`faster focal ratios (fik2.8) with degraded image quality per
`formance at the same FOV (e.g. 36 degrees), or with reason
`ably good performance at a smaller FOV.
`The refractive lens elements in the various embodiments
`may be composed of plastic materials. In at least some
`embodiments, the refractive lens elements may be composed
`of injection molded optical plastic materials. However, other
`Suitable transparent materials may be used. Also note that, in
`a given embodiment, different ones of the lens elements may
`be composed of materials with different optical characteris
`tics, for example different Abbe numbers and/or different
`refractive indices.
`In embodiments of the compact telephoto lens system, the
`lens element materials may be selected and the refractive
`power distribution of the lens elements may be calculated to
`satisfy a lens system effective focal length requirement and to
`correct chromatic aberrations and the field curvature or Petz
`Val Sum. The monochromatic and chromatic variations of
`optical aberrations may be reduced by adjusting the radii of
`curvature and aspheric coefficients or geometrical shapes of
`the lens elements and axial separations to produce well-cor
`rected and balanced minimal residual aberrations, as well as
`to reduce the total track length (TTL) and to achieve quality
`optical performance and high image resolution in a small
`form factor telephoto camera.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a cross-sectional illustration of an example
`embodiment of a compact telephoto camera including a com
`pact telephoto lens system that includes five refractive lens
`elements.
`FIG. 2 illustrates a plot of the polychromatic ray aberration
`curves over the half field of view and over the visible spectral
`band ranging from 470 nm to 650 nm for a compact telephoto
`lens system as illustrated in FIG. 1.
`FIG. 3 is a cross-sectional illustration of another example
`embodiment of a compact telephoto camera including a com
`pact telephoto lens system that includes five refractive lens
`elements.
`FIG. 4 illustrates a plot of the polychromatic ray aberration
`curves over the half field of view and over the visible spectral
`band ranging from 470 nm to 650 nm for a compact telephoto
`lens system as illustrated in FIG. 3.
`FIG. 5 is a cross-sectional illustration of another example
`embodiment of a compact telephoto camera including a com
`pact telephoto lens system that includes five lens elements
`with refractive power.
`FIG. 6 illustrates a plot of the polychromatic ray aberration
`curves over the half field of view and over the visible spectral
`band ranging from 470 nm to 650 nm for a compact telephoto
`lens system as illustrated in FIG. 5.
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`FIG. 7 is a cross-sectional illustration of an example
`embodiment of a compact telephoto camera including a com
`pact telephoto lens system that includes four lens elements
`with refractive power.
`FIGS. 8, 9, and 10 show plots of the polychromatic ray
`aberrations curves over the half field of view (HFOV) over the
`visible spectral band ranging from 470 nm to 650 nm for
`embodiments of a compact telephoto lens system as illus
`trated in FIG. 7.
`FIG. 11 is a cross-sectional illustration of an example
`10
`embodiment of a compact telephoto camera including a com
`pact telephoto lens system that includes five lens elements
`with refractive power in which the aperture stop is located at
`the first lens element and behind the front vertex of the lens
`system.
`FIG. 12 illustrates a plot of the polychromatic ray aberra
`tion curves over the half field of view and over the visible
`spectral band ranging from 470 nm to 650 nm for a compact
`telephoto lens system as illustrated in FIG. 11.
`FIG. 13 is a cross-sectional illustration of an example
`embodiment of a compact telephoto camera including a com
`pact telephoto lens system that includes five lens elements
`with refractive power in which the aperture stop is located
`between the first and second lens elements.
`FIG. 14 illustrates a plot of the polychromatic ray aberra
`tion curves over the half field of view and over the visible
`spectral band ranging from 470 nm to 650 nm for a compact
`telephoto lens system as illustrated in FIG. 13.
`FIG. 15 is a high-level flowchart of a method for capturing
`images using a camera as illustrated in FIGS. 1, 3, 5, 11, and
`13, according to at least Some embodiments.
`FIG. 16 is a flowchart of a method for capturing images
`using a camera as illustrated in FIG. 7, according to at least
`Some embodiments.
`FIG. 17 illustrates an example computer system that may
`be used in embodiments.
`This specification includes references to “one embodi
`ment” or “an embodiment.” The appearances of the phrases
`“in one embodiment” or “in an embodiment” do not neces
`sarily refer to the same embodiment. Particular features,
`structures, or characteristics may be combined in any Suitable
`manner consistent with this disclosure.
`“Comprising.” This term is open-ended. As used in the
`appended claims, this term does not foreclose additional
`structure or steps. Consider a claim that recites: An appara
`tus comprising one or more processor units...”. Such a claim
`does not foreclose the apparatus from including additional
`components (e.g., a network interface unit, graphics circuitry,
`etc.).
`“Configured To. Various units, circuits, or other compo
`nents may be described or claimed as “configured to perform
`a task or tasks. In Such contexts, “configured to’ is used to
`connote structure by indicating that the units/circuits/compo
`nents include structure (e.g., circuitry) that performs those
`task or tasks during operation. As such, the unit/circuit/com
`ponent can be said to be configured to perform the task even
`when the specified unit/circuit/component is not currently
`operational (e.g., is not on). The units/circuits/components
`used with the “configured to language include hardware—
`for example, circuits, memory storing program instructions
`executable to implement the operation, etc. Reciting that a
`unit/circuit/component is “configured to perform one or
`more tasks is expressly intended not to invoke 35 U.S.C.
`S112, sixth paragraph, for that unit/circuit/component. Addi
`tionally, "configured to can include generic structure (e.g.,
`generic circuitry) that is manipulated by Software and/or firm
`ware (e.g., an FPGA or a general-purpose processor execut
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`ing Software) to operate in manner that is capable of perform
`ing the task(s) at issue. “Configure to may also include
`adapting a manufacturing process (e.g., a semiconductor fab
`rication facility) to fabricate devices (e.g., integrated circuits)
`that are adapted to implement or perform one or more tasks.
`“First “Second, etc. As used herein, these terms are used
`as labels for nouns that they precede, and do not imply any
`type of ordering (e.g., spatial, temporal, logical, etc.). For
`example, a buffer circuit may be described hereinas perform
`ing write operations for “first and “second values. The
`terms “first and “second do not necessarily imply that the
`first value must be written before the second value.
`“Based On.” As used herein, this term is used to describe
`one or more factors that affecta determination. This term does
`not foreclose additional factors that may affect a determina
`tion. That is, a determination may be solely based on those
`factors or based, at least in part, on those factors. Consider the
`phrase “determine A based on B. While in this case, B is a
`factor that affects the determination of A, such a phrase does
`not foreclose the determination of Afrom also being based on
`C. In other instances. A may be determined based solely on B.
`
`DETAILED DESCRIPTION
`
`Embodiments of a small form factor camera including a
`photosensor and a compact telephoto lens system are
`described. Various embodiments of a compact telephoto lens
`system including four or five lens elements are described that
`may be used in the camera and that provide a larger image and
`with longer effective focal length than has been realized in
`conventional compact cameras. The camera may be imple
`mented in a small package size while still capturing sharp,
`high-resolution images, making embodiments of the camera
`suitable for use in small and/or mobile multipurpose devices
`Such as cell phones, Smartphones, pad or tablet computing
`devices, laptop, netbook, notebook, Subnotebook, and ultra
`book computers, and so on. However, note that aspects of the
`camera (e.g., the lens system and photosensor) may be scaled
`up or down to provide cameras with larger or Smaller package
`sizes. In addition, embodiments of the camera system may be
`implemented as stand-alone digital cameras. In addition to
`still (single frame capture) camera applications, embodi
`ments of the camera system may be adapted for use in video
`camera applications.
`Several example embodiments of compact telephoto lens
`systems are described, including embodiments with five
`refracting lens elements and embodiments with four refract
`ing lens elements. FIGS. 1 and 3 show variations on an
`example embodiment that includes five refracting lens ele
`ments. FIG. 5 shows another example embodiment that
`includes five refracting lens elements. FIG. 7 shows an
`example of an embodiment that includes four refracting lens
`elements. FIGS. 11 and 13 show example embodiments with
`five refracting lens elements in which the aperture stop is
`located differently than in the embodiments of FIGS. 1,3, and
`5. Note, however, that these examples are not intended to be
`limiting, and that variations on the various parameters given
`for the lens systems are possible while still achieving similar
`results. For example, variations on the embodiment that
`includes four refracting lens elements shown in FIG. 7 are
`described.
`The refractive lens elements in the various embodiments
`may be composed of a plastic material. In at least some
`embodiments, the refractive lens elements may be composed
`of an injection molded plastic material. However, other trans
`parent materials may be used. Also note that, in a given
`embodiment, different ones of the lens elements may be com
`
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`posed of materials with different optical characteristics, for
`example different Abbe numbers and/or different refractive
`indices.
`Small Form Factor Telephoto Camera
`In each of FIGS. 1, 3, 5, 7, 11, and 13, an example camera
`includes at least a compact telephoto lens system and a pho
`tosensor. The photosensor may be an integrated circuit (IC)
`technology chip or chips implemented according to any of
`various types of photosensor technology. Examples of pho
`tosensor technology that may be used are charge-coupled
`device (CCD) technology and complementary metal-oxide
`semiconductor (CMOS) technology. In at least some embodi
`ments, pixel size of the photosensor may be 1.2 microns or
`less, although larger pixel sizes may be used. In a non-limit
`ing example embodiment, the photosensor may be manufac
`tured according to a 1280x720 pixel image format to capture
`1 megapixel images. However, other pixel formats may be
`used in embodiments, for example 5 megapixel, 10 mega
`pixel, or larger or Smaller formats.
`The camera may also include a frontal aperture stop (AS)
`located in front of (i.e., on the object side of) a first lens
`element. While FIGS. 1,3,5, and 7 show the frontal aperture
`stop located at or near the front vertex of the lens system,
`location of the aperture stop may be closer to or farther away
`from the first lens element. Further, in some embodiments, the
`aperture stop may be located elsewhere in the telephoto lens
`system. For example, the aperture stop may be located at the
`first lens element but behind the front vertex of the lens
`system as shown in FIG. 11, or between the first and second
`lens elements as shown in FIG. 13.
`The camera may also, but does not necessarily, include an
`infrared (IR) filter located between a last lens element of the
`telephoto lens system and the photosensor. The IR filter may,
`for example, be composed of a glass material. However, other
`materials may be used. Note that the IR filter does not affect
`the effective focal length f of the telephoto lens system. Fur
`ther note that the camera may also include other components
`than those illustrated and described herein.
`In the camera, the telephoto lens system forms an image at
`an image plane (IP) at or near the Surface of the photosensor.
`The image size for a distant object is directly proportional to
`the effective focal length f of a lens system. The total track
`length (TTL) of the telephoto lens system is the distance on
`the optical axis (AX) between the front vertex at the object
`side surface of the first (object side) lens element and the
`image plane. For a telephoto lens system, the total track
`length (TTL) is less than the lens system effective focal length
`(f), and the ratio of total track length to focal length (TTL/f) is
`the telephoto ratio. To be classified as a telephoto lens system,
`TTL/f is less than or equal to 1.
`In at least Some embodiments, the telephoto lens system
`may be a fixed telephoto lens system configured such that the
`effective focal length f of the lens system is at or about 7.0
`millimeters (mm) (e.g., within a range of 6.0-8.0 mm), the
`F-number (focal ratio, or f/ii) is within a range from about 2.4
`to about 10.0, the field of view (FOV) is at or about 36 degrees
`(although narrower or wider FOVs may beachieved), and the
`total track length (TTL) of the lens system is within a range of
`about 5.2 to about 7.0 mm. More generally, the telephoto lens
`system may be configured such that that the telephoto ratio
`(TTL/f) satisfies the relation:
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`In the example embodiments described herein (see FIGS.
`1, 3, 5, 7, 11, and 13), the telephoto lens system may be
`configured such that the effective focal length f of the lens
`system is 7.0 mm at reference wavelength 555 nm, and the
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`F-number is 2.8. The lens system may, for example, be con
`figured with a focal length fof 7.0 mm and F-number of 2.8 to
`satisfy specified optical, imaging, and/or packaging con
`straints for particular camera system applications. Note that
`the F-number, also referred to as the focal ratio or fi, is
`defined by f/D, where D is the diameter of the entrance pupil,
`i.e. the effective aperture. As an example, at f=7.0 mm, an
`F-number of 2.8 is achieved with an effective aperture of 2.5
`mm. The example embodiment may also be configured with
`a field of view (FOV) at or about 36 degrees. Total track length
`(TTL) of the example embodiments vary from about 5.6 mm
`to about 6.0 mm. Telephoto ratio (TTL/f) thus varies within
`the range of about 0.8 to about 0.857.
`However, note that the focal length f, F-number, and/or
`other parameters may be scaled or adjusted to meet various
`specifications of optical, imaging, and/or packaging con
`straints for other camera system applications. Constraints for
`a camera system that may be specified as requirements for
`particular camera system applications and/or that may be
`varied for different camera system applications include but
`are not limited to the focallength f, effective aperture, F-num
`ber, field of view (FOV), imaging performance requirements,
`and packaging Volume or size constraints.
`In some embodiments, the telephoto lens system may be
`adjustable. For example, in some embodiments, a telephoto
`lens system as described herein may be equipped with an
`adjustable iris (entrance pupil) or aperture stop. Using an
`adjustable aperture stop, the F-number (focal ratio, or f/ii)
`may be dynamically varied within a range. For example, if the
`lens system is well corrected at f/2.8, at a given focal length f
`and FOV, then the focal ratio may be varied within the range
`of 2.8 to 10 (or higher) by adjusting the aperture stop assum
`ing that the aperture stop can be adjusted to the F-number
`setting. In some embodiments, the lens system may be used at
`faster focal ratios (fil-2.8) by adjusting the aperture stop,
`with degraded image quality performance at the same FOV
`(e.g. 36 degrees), or with reasonably good performance at a
`Smaller FOV.
`While ranges of values may be given herein as examples
`for adjustable cameras and lens systems in which one or more
`optical parameters may be dynamically varied (e.g., using an
`adjustable aperture stop), embodiments of camera systems
`that include fixed (non-adjustable) telephoto lens systems in
`which values for optical and other parameters are within these
`ranges may be implemented.
`Referring first to embodiments as illustrated in FIGS. 1